1. Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen, Bismarckstraße 81, 47057 Duisburg, Germany
2. LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Sciences and Engineering, Nanyang Technological University 639798, Singapore
3. Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey